1. Field of the Invention
The present invention relates to door assemblies of the type including a door member for selectively covering an opening in a wall, an endless chain member, a coupling means for coupling the chain member to the door member, and a drive means for driving the chain member to cause the door member to move between an opened and a closed position.
2. Description of the Prior Art
Various door assemblies of the above described type have heretofore been developed. See, for example, Graves, U.S. Pat. No. 1,506,925. While the door assembly disclosed in the Graves patent has a manual, crank-type drive means, it is well-known to those skilled in the art to utilize electric motors and appropriate control means to drive the endless chain members. Such prior art door assemblies do not disclose or suggest the present invention.